<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style type="text/css">
			.box{
				width: 100px;
				height: 100px;				
			}
		</style>
		<!-- 1、CDN中配置jQuery -->
		<!-- <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script> -->
		
		<!-- 2、本机中配置jQuery -->
		<script src="js/jquery-3.4.1.min.js"></script>
		
	</head>
	<body>
		<div class="box"></div>
		 
		 <script>
			 $(function(event){
				 $('.box').css('background', 'blue');
			 });
		 </script>
		 
	</body>
</html>
